Grinding mill



Augfz'7, V1935. E. G. BAILEYvl-:r-Al. 2,012,265

GRINDING MILL 3 Sheets-Sheet 1 NVENTORS Original Filed June '5, 1929 Aug. 2'7, 1935. E. G. BAILEY Er AL 2,012,255

' GRINDING'MILL Original Filed June 5, 1929 5 Sheets-Sheet 2 FIGB.

y ATTORN EYJ Aug. 27, 1935. E. G. BAILEY Er AL 2,012,265

' GRINDING MILL Original Filed June 5, 1929 5 Sheets-Sheet 3 INVENTORS www ATTORN E'YS Patented Aug. 27, 1935 UNITED STATES PATENT OFFICE Short Hills, and Ralph M. Hardgrove,

Westiield, N. J., assignors to Fuller Lehigh Company, Fullerton, Pa., a corporation of Delaware Application June 5, 1929, Serial No. 368,506

Renewed July 25, 1934 23 Claims.

This invention relates to a grinding mill voi? the ball type in which the iine particles of the ground material are removed from the mill by an air current. Provision is also made by means of which coarse particles of material may be separated from the airv current and returned to be reground. The invention is especially applicable for grinding or pulverizing coal, but it is not restrictedlto this particular use.

The invention will be understood from the description in connection with the accompanying drawings in which Fig. 1 is a vertical section through an illustrative embodiment of the inven' tion; Fig. 2 is avsection along the line 2-2 of Fig. l; Fig. 3 is a section along the line 3-3 of Fig. 1; Fig. 4 is a section along the line 4-4 of Fig. 1; and Fig. 5 is a section along the line 5-5 of Fig. 1.. y

' In the drawings reference character l indicates a base to which the bottom part 2 of the machine ;may be bolted by means of the bolts 3. A ilat thick disc 4 is located in the lower portion of the hollow bottom 2 ofthe machine and is provid-ed with a central opening 5. A ball ring 5 adapted to withstand thrust is mounted upon the disc 4. i

The casing 1 of the machine extends upwardly from the bottom portion 2 and encloses the grinding vparts of the machine. The lowerl portion of the casing 1 is made outwardly iiaring, as indicated at 8, to provide the outer wall of an annular air space 9 into which an air inlet I0 leads. Anair compressor or fan may force the air through the mill or a suction fan may draw the air through it.

An air tight Wall II extends from theoutside of the ring 6 to the upper portion of the ilaring Wall 8 to provide the other side or wall ofthe annular air space 9. A plurality of air ports I2 extend through the ring 6 to permit air to pass therethrough from the space 9. W

`A deector I3 approximately Aas long as the ring 6 and of smaller diameter than the inside diameter of this ring is connected to the disc 4 so as to leave an annularspace I4 between it and the ring 6. A ball race I6 for the grinding balls I1 is provided along the upper edge of the ring 6 and serves as a grinding surface.

A rotatable driving and grinding ring I8 is located above the row of balls I1 and is provided with ball races along its lower and upper edges.

A row of balls I9 is provided above the ring I8,

these balls being preferably larger than the balls I1. A pressure ring 20 of smaller diameter than tact with the same.

A sheet metal ring 22 is attached to the inside of the wall II approximately at the level of the upper side of the ring I8. This ring 22 is L shaped in cross section and may be connected to the wall I I inany convenient manner, but preferably by means of bolts 22 through vertically disposed slots to permit the ring 22 to be adjusted up and down. The inside of this ring is slightly larger than the outside diameter of the driving ring I8 to leave an annular space 23 between the ring I8 and the ring 22.- The size of the opening 23 can be varied by adjusting the position oi the ring 22 up and'down with respectto the ring I8 by means of the bolts 24 extending through screw threaded holes in the support 25.

A verticalshaft 26 extends through the opening 5 in the disc 4 and isdriven by means of av motor 21 through reduction gearing. A hub 28 is provided on the shaft 26 and a driving member 29 for the ring I8 is attachedv to the hub 28. The driving member 29 is provided with arms 29' that extend into vertically disposed slots between lugs 38 along the inside surface of the ring I8, so that the ring I8 is permitted to move up' and down with respect to the Idriving member 29. A screen 3| approximately in the form of a truncated cone extends upwardly from the inner edge of the ring I8 along the inside of the row of balls I9. This screen is provided with slots 3|.

A conical deflector 32 isattached to the driving member 29 and is provided with a ange 33 at its lower end and ian blades 34 above the ange 33 in position to create a current of air that impinges against the row oi balls I1.

A cylindrical housing 35 extends from the upper edge of the screen 3| to a point some distance above the upper edge of the ring 20 leaving an annular space 36 between screen and housing. TheV circumferential wall of the housing 35 is provided with openings over which wire screens 31 extend.A

The ring 20 is prevented from revolving vby means of lugs 38 along the inside surface of the casing 1, which lugs contact with lugs 39 on the outside of the ring 20 or project into` vertically disposed slots along the outside of this ring. Contact pieces 4I) with rounded ends are provided along the upper surface of the pressure ring 20 for the lower ends of plungers 4I that may be pressed downwardly in any convenient manner. as 'for example, by means of springs. Each plunger 4I passes through a stuing box 42. The stuiing boxes are located in inset portions of v the casing1, as most clearly indicated in Fig. 2. The

-upper end of the plunger 4I is connected to a piston 43 in the cylinder 44 attached to the casing 1. Compression springs 45 are interposed between the piston 43 and the disc 46. The disc 46 is adjustable by means of the screw 41 to vary the compression of the springs 44. Stops 48 that may be adjustable along the inside of the casing 1 may be provided to limit the downward movement of the plungers 4I.

' A feed chute 50 extends through the closed top of the upper end of the casing- 1 into position to feed material between the housing 35 and ring 29. A cylindrical outlet I is provided at the top of the machine and a conically shaped classifier 52 is located .below theoutlet 5I with its upper edge extending higher than the lower edge of the outlet 5I. The lower small end of the classifier 52 is left open', as indicated at 53. An opening 54, which is normally closed by means of a door, is provided in the side of the casing 1 for access to the inside.

The operation is as follows:

The material to be ground is fed through the chute 50 and passes down through the annular space between the inside of the stationary ring 20 and the housing 35. The material is then ground to some extent by means of the large balls I9 that are carried around by the rotating ring I8. Some of the fine material is picked up by a current of upwardly ascending air. The particles ground by the balls I9 pass through the annular space 23 between the rings I8 and 22 to ll the lower portion of the space along the inside of the converging portion of the wall II. The arrangement of the ring 22 relative to the grinding ring I8 provides a regulable restriction controlling the ow of material between the upper and lower grinding stages, which is disclosed and claimed in our copending application Serial No. 390,698, filed September 6, 1929. A'Ihe material is further ground by means of the row of balls I1.

Air under pressure passes through the inlet III into the annular space 9 and thence through the ports I2 and upwardly through the annular space between the wall I3 and the inside ofthe ring 6. The upwardly rising sheet of air picks up the ground material that is passed through the row of balls I1 and the fans 34 also help to pick up the fine particles. The air carrying the fine particles passes upwardly through the inside of the ring I8 and a small portion passes through slots 3l and picks up some fine coal from balls I9. The mixture of air and pulverized material then passes through the screens 31 or through annular space 36 or both. The air and fine particles then pass upwardly and around the upper edge of the cone 52 and thence under the lower edge of the cylindrical outlet 5I causing the coarse particles to be thrown out and pass downwardly through the opening 53 onto the top of the housing 35 from which it is thrown oil and passes downwardly with thc incoming material to be again ground. The air and ne particles pass out through the outlet 5I to a place ofguse or storage.

By providing pressure applying means to the top of the pressure ring 20, the capacity of the machine is automatically increased by feeding material more rapidly.' 'This occurs because the layers of material that are being ground by the balls raise the rings I8 and 20, thus compressing the springs and causing them to exert greater pressure upon the grinding elements. At light loads the ring 20 descends far enough to permit the plungers 4I to rest upon the stops 48, thus decreasing the amount of lpower that would be re'- required at light loads if pressure were exerted upon the ring 20.

By having the balls in the upper row I9 of larger size than the balls in the lower row I1, the coarse or rough grinding of the material is accomplished by the first row of balls I9 and the smaller balls I1 finish the grinding. Also balls that have been worn down a certain amount in the upper ring are still good for further service in the lower ring as the grinding action is such that the balls remain spherical.

While in accordance with the provisions of the statutes we have illustrated and described herein the best form of our invention known to us, those skilled in the art will understand that changes may be made in theV form of the apparatus and character of the carrier medium disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes be used without a corresponding use of other features. In our claims, the term air is used generically to cover rows of grinding elements, means for feeding material to be ground to the outside of one of said rows, and means to cause a current of air to pass upwardly in proximity to said grinding elements along the inside of said rows.

2. In a grinding mill, a plurality of circular rows of grinding elements, means for feeding material to be ground to the outsideI of one of said rows, and means to cause a current of air to pass upwardly in an annular band in proximity to said grinding elements along the inside of said rows.

3. In a grinding mill, a plurality of circular rows of grinding elements, means for feeding material to be ground to the outside of one of said rows, means to withdraw ground material along the inside of said rows, and means to return coarse particles to said grinding elements.

4. In a grinding mill, a plurality of circular rows of grinding elements, i means for feeding material to be ground to the outside of one of said rows, a screen, and means to withdraw ground material along the insideof said rows, 'said screen being located in the path of the material being withdrawn.

5. An air-swept grinding mill comprising a substantially tir-tight casing having an inlet for material to be ground and an outlet for ground material in the upper part thereof, a plurality of vertically spaced grinding rings in said casing, upper and lower circular rows of rolling grinding elements positionedbetween different pairs of grinding rings and cooperating therewith to form upper and lower grinding stages, each receiving material to be ground at one side of said row of elements and discharging ground material at the other side, and means for directing an annular stream of air upwardly through said casing adjacent to and mainly past the discharge side of one of said rows of elements and conveying the material' ground thereby to said casing outlet.

6. An air-swept grinding mill comprising a substantially tir-tight casing having an inlet for material to be ground and an outlet for ground material in the upper part thereof, a plurality of vertically spaced grinding rings in said casing, upper and lower circular rows of rolling grinding elements positioned between different pairs 'of'grinding rings and cooperating therewith to form successive grinding stages, each receiving material to be ground at one side of said ro-w of elements and discharging ground material at the other side, and means for directing an annular stream of air upwardly through said casing adjacent to and mainly past the discharge side of said lower row of elements and conveying the material ground thereby to said casing outlet.

7. An air-swept grinding mill comprising a substantially air-tight casing having an inlet for material to be ground and an outlet for ground material in the upper part thereof, a plurality `of vertically spaced grinding rings in said casing,

upper and lower circular rows of rolling grinding elements positioned between different pairs of grinding rings and cooperating therewith to form a plurality of grinding stages, each receiving material to be ground at one side of said row of elements and discharging ground material at the other side, means for directing an annular stream of air upwardly through said casing adjacent to and mainly past the discharge side of one of said rows of elements and conveying the material ground thereby to said casing outlet, and means in the path of flow of said air stream for separatingl out coarse material and returning the separated material to the feed side of one of said grinding stages.

8. An air-swept grinding mill comprising a substantially air-tight casing having an inlet for material to be ground and an outlet for ground material in the upper part thereof, a plurality of vertically spaced grinding rings in said casing, a circular row of rolling grinding elements positioned between said grinding rings and cooperating therewith to form a grinding stage receiving material to be ground at the outer side of said row of elements and discharging ground material at the inner side, and means for directing an annular stream of air upwardly through said casing adjacent to and mainly past the inner side of said row of elements and conveying the material discharged therefrom to said casing outlet.

9. An air-swept grinding mill comprising a substantially air-tight casing having an inlet for material `to be ground and an outlet for ground material in the upper part thereof, a plurality of vertically spaced grinding rings in said casing, a circular row of rolling grinding elements positioned between said grinding rings and cooperating therewith to form a grinding -stage receiving material to be ground at one side of said row of elements and discharging ground material at the other side, means for directing an annular stream of air upwardly through said casing adjacent to and mainly past the discharge side of said row of elements and conveying the material ground thereby to said casing outlet, and means in the path of flow of said air stream for separating out coarse materialand returning the separated material to the feed side of said grinding stage. 10. A grinding mill comprising a casing having an inlet for material to be ground and an outlet for ground material, a grinding ring in saidn casing. a circular row of rolling grinding elements;

supported on said grinding elements and regulable resilient means acting downwardly on said pressure ring to superpose a grinding pressure thereon, and means for rendering said resilient means ineifective at predetermined positions of said floating pressure ring.

11. In a grinding mill, a plurality of rows of rotating grinding elements, means for feeding material to one row of said elements in one direction and to another row in the opposite'direction, and means to cause an air current to pass upwardly through the inside of said rows of elements.

\ 12. In a grinding mill, a plurality of rows of rotating grinding elements, means to cause material to pass from the inside to the outside of one row of said elements and from the outside to the inside of another row of balls, and means to cause an air current to pass upwardly through the inside of said rows of elements.

13. In a grinding mill, a plurality of rows of rotating grinding elements, means comprising a conically shaped plate to cause material to pass from the inside to the outside of one row of said elements and from the outside to the inside of another row of said elements, and means to cause an air current to pass upwardly through the inside of said rows of elements.

14. In a1- grinding mill, a plurality of rows of rotating grinding elements, means comprising a conically shaped plate to cause material to pass from the inside to the outside of one row of said elements and from the outside to the inside of another row of said elements, and means to cause an air current to pass upwardly through the inside of said rows of elements and through the inside of said conically shaped plate.

15. An air-swept grinding mill comprising a casing having an outlet for ground material in the upper part thereof and enclosing vertically spaced upper, intermediate and lower grinding rings, circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings and cooperating therewith -to form an upper grinding stage having an outward flow of material therethrough and a lower grinding stage receiving material from said upper stage and having an vinward flow of material therethrough, a drive shaft arranged axially of said grinding rings, means forming a rotary drive connection between said shaft and intermediate grinding ring, ymeans preventing rotation of said upper and lower grinding rings, means for delivering material to positioned between said upper and intermediate.

and said intermediate and lower grinding rings and cooperating therewith to form an upper grinding stage having an outward flow of material therethrough and a lower grinding stage receiving material from said upper stage and having an inward flow of material therethrough, a drive shaft arranged axially of said grinding rings, means forming a rotary drive connection between said shaft and intermediate grinding ring, means preventingrotation 'of said upper and lower grinding rings, means for delivering material toy be ground to the inner side of said upper row of elements, an air box at the lower part of said casing, air passages below said lower grinding ring connecting said air box to the inner side of said lower-row of elements, and means for directing a stream of air from said air box through said passages and thence upwardly through said casing adjacent to and mainly past the inner side of said lower row of elements and conveying material discharged therefrom towards said casing outlet.

17. An air-swept grinding mill comprising a casing having an outlet for ground material in the upper part thereof and enclosing vertically spaced upper, intermediate and lower grinding rings, circular rows of rolling grinding elements positioned between said upper and intermediatev and said intermediate and lower grinding rings and cooperating therewith to form an upper grinding stage having an outward flow of material therethrough and a lower grinding stage receiving material from said upper stage and having an inward flow of material therethrough,

a drive shaft arranged axially of said grinding rings, means forming a rotary drive connection between said shaft and intermediate grinding ring, means preventing rotation of said upper and lower grinding rings, means for delivering material to be ground to the inner side of said upper row of elements, an air box at the lower part of said casing, means for directing an annular stream of air from said air box upwardly through said casing adjacent to and mainly past the inner side of said lower row of elements and conveying material discharged therefrom towards said casing outlet, and means in the path of ow of said air stream for causing the air stream to pass through the stream of material being delivered to the inner side of said upper row of elements. :f

18. An air-swept grinding mill comprising a casing having an outlet for ground material in the upper part thereof and enclosing vertically spaced upper, intermediate and lower grinding rings, circular rows of rolling grinding elements positioned between said upper and intermediate and said intermediate and lower grinding rings and cooperating therewith to form an upper grinding stage having an outward flow of material therethrough and a lower grinding stage receiving material from said upper stage and having an inward flow of material therethrough, a drive shaft arranged axially of said grinding rings, means forming a rotary drive connection between said shaft and intermediate grinding ring, means preventing rotation of said upper and lower grinding rings, means for delivering material to be ground to the inner side of said upper row of elements, an air box at the lower part of said casing, means for directing a stream of air from said air box upwardly through said casing adjacent to and mainly past the inner side of said lower row of elements and conveying the material discharged therefrom towards said casing outlet, and means in the .path of flow of said air stream for separating out coarse material and returning the separated material to the inner side of said upper row of elements.

19. An air-swept grinding mill comprising a substantially air-tight casing having an outlet for ground material in the upper part thereof and enclosing vertically spaced upper. intermediate and lower grinding rings, circular rows of rolling grinding elements positioned between said upper and intermediate and said intermedi- V'ate and'ldwer grinding rings and cooperating ranged axially of said grinding rings,.means' forming a rotary drive connection between said shaft and intermediate grinding ring, means preventing rotation of said upper and lower grinding rings, means for delivering material to be ground to the inner side of said upper row of elements, an annular air box surrounding said casing, air passages below said lower grinding ring connecting said air box to the inner side of said lower row of elements, means for directing an annular stream of air from said air box through said passages and thence upwardly through said casing adjacent to and mainly past the inner side of said lower row of elements and conveying the vmaterial discharged therefrom towards said casing outlet, `and means in the path of flow of said air stream for separating out coarse material and returning the separated material to the inner side of said upper row of elements.

20. An air-swept grinding mill comprising a substantially air-tight casing having an inlet for material to be ground and an outlet for ground material in the upper part thereof, a plurality of vertically spaced grinding rings in said casing including a rotary upper grinding ring and a non-rotary lower grinding ring, a circular row of rolling grinding elements positioned between said grinding rings and cooperating therewith to form a grinding stage receiving material to be ground at the outer side of said row of elements and discharging ground material at the inner side, drive means having a drive connection with said upper ringa resilientmeans for applying a grinding pressure between saidgrinding rings and row o'f elements, and means for directing an annular stream of air upwardly through said casing adjacent to and mainly past the inner side of said row of elements and conveying the material discharged therefrom to said casing outlet.

l 21. An air-swept grinding millcomprising an annular air box, a substantially air-tight casing extending above said air box and having an inlet for material to be ground and an outlet for ground material in the upper part thereof, a plurality of vertically spaced grinding rings in said casing, a circular row of rolling grinding elements positioned between said grinding rings and cooperating therewith to form a grinding stage receiving material to be ground at the outer side of said row of elements and discharging ground material at the inner side, and means for directing an annular stream of air from said air box below said lower ring and thence upwardly through said casing adjacent to and mainly past the inner side of said row of elements and conveying the material discharged therefrom to said casing outlet.

22. An air-swept grinding mill comprising an annular air box, a substantially air-tight casing extending above said air box and having an inlet for material to be ground and' an outlet for ground material in the upper part thereof, a plurality of vertically spaced grinding rings in said casing including a rotary upper grinding ring and a non-rotary lower grinding ring, a circular row of rolling grinding elements positioned between said grinding rings and cooperating ltherewith to form a grinding stage receiving material to be ground at the outer side of said row of elements and 4discharging ground amazes material at the inner side, drive means having a drive connection with said upper ring, resilient means for applying a grinding pressure between said grinding rings and row of elements, and means for directing an annular stream of air from said air box below said lower ring and thence upwardly through said casing adjacent to and mainly past the inner side of said row of elements and conveying the material discharged therefrom to said casing outlet.

23. An air-swept grinding mill comprising an annular air box, a substantially air-tight casing extending above said air box and having an inlet for material to be ground and an outlet for ground material in the upper part thereof, a plurality o1 vertically spaced grinding rings in said casing including a rotary upper grinding ring anda non-rotary lower grinding ring, a circular row of rolling grinding elements positioned between said grinding rings and cooperating therewith to form a grinding stage receiving material to be ground at the outer side of said row of elements and discharging ground material at the inner side, a drive shaft extending upwardly axially of said row of elements and having a drive connection with said upper ring, resilient means for applying a lgrinding pressure between said grinding rings and row of elements, means for directing an annular stream of air from said 'air box below saidflower ring and thence upwardl; through said casing adjacent to and mainly past the inner side of said row of elements and conveying the material discharged therefrom to said casing outlet, and means in thepath of now of said. air stream for separating out coarse material for return to the outer side oi.'

said grinding stage.

ERVIN G. BAILEY. PERRY R. CASSIDY.

RALPH M. HARDGROVE. 20 

